1. Field of the Invention
This invention relates to a manufacturing method of an electroluminescent display device, particularly to a method of sealing an electroluminescent display device including a first substrate having an electroluminescent element thereon and a second substrate for sealing the first substrate.
2. Description of the Related Art
In recent years, electroluminescent (hereafter, referred to as EL) display devices with EL elements have been receiving an attention as a display device replacing a CRT and an LCD.
In a conventional organic EL display panel, a plurality of pixels each having an organic EL element and TFTs for driving the organic EL element is disposed in a matrix on a device glass substrate to form a display region. Since the organic EL element has a characteristic of being sensitive to moisture, there is proposed a sealing structure in which moisture infiltration is prevented by covering the glass substrate with a metal cap or a sealing glass substrate which is coated with a desiccant.
In a sealing structure with the sealing glass substrate, the device glass substrate having the organic EL element and the sealing glass substrate are attached with a sealing resin by applying a load with a flat plate.
With size increase in the device glass substrate, however, it becomes difficult to apply the load uniformly to the device glass substrate having a large area. In some case, a cushion is used to distribute the load evenly. Therefore, there arises a variety of problems in the attaching process. For example, a fluctuation of a width of the sealing resin occurs, which results in a formation of a narrow portion of the sealing resin or a large gap between the device glass substrate and the sealing glass substrate, thereby allowing moisture to infiltrate through such a portion.
Furthermore, in the attaching process, a load is applied to the device glass substrate to provide a predetermined gap between the device glass substrate and the sealing glass substrate. The applied load causes a flexure in the device glass substrate, which in some case results in breaking the device glass substrate.